Air conditioning system



Oct. 20, 1942. R. B. P. cRAwr-'ORD AIR CONDITIONING SYSTEM Filed Nov. 12, 1938 5 Sheets-Sheet 1 ,hmmtor Y BJP?, @mwfmml Uttorngg S N9 IIJ rlllllll.

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AIR CONDITIDNING SYSTEM Filed Nov. l2, 1938 3 Sheets-Sheet 5 Figo INVENTOR. Roken'l' 13.2 (frawfor Patented Oct. 20, 1942 UNITED STATES PATENT GFFICE AIR CONDITIONING SYSTEM Robert B. P. Crawford, Miami, Fla.

Application November 12, 1938, Serial No. 239,967

.f combined`h%ang nd cgqlipgrmppnditioing system whic utilizes a refrigeration system araranged for reversal in opera ion and which the cooling cycle and for supplying heat when the system operates on the heating cycle.

More specifically, it is an object of this invention to provide a system of the type mentioned, in which the water supply is used for recpglijnmg the airmlmuwrhiknagmtwemsurnmer and for prgw ."illli-airilrinathewin er, this action occurring before the water is supplied to the refrigeration system.

A further object of this invention is to provide a system of automatic control for an air conditioning system of the general type mentioned above, and which operates to maintain proper space conditions and also to reduce operating expenses to 4a minimum.

Another object of this invention is the provision of a combined heating and cooling system with a storage arrangement for storing either the hot or cold heat exchange medium, for thereby reducing the necessary size of the compressor.

Another object of this invention is the provision of an air conditioning system which includes a refrigeration system for both heating ...agdwcsglieemgspggg and which issewnged for providing a supply of domestic hot water both upon the heating and cooling cycles.

More specifically, it is an object to provide a` system in which well or other cooling water is provided for cooling the condenser of a refrigeration system, with an arrangement for inter- I,rupting the supply of well Water to the coninflr dome QLWALCLMWMHW Another object is the provision of an automatic throttling arrangement for varying thmnoyvwgjm@ trols utilized in controlling the system shown 60 in Figure 1, and

13 Claims.

" denser and for ut` 'pg the condenser for heat- Figure 3 shows an alternate arrangement for a portion of the system shown in Figures 1 and 2.

Referring to Figure 1, reference character I indicates generally a compressor which may be driven by a variable speed electric motor 2 which is provided with a three-speed control box 3. Leading from the discharge connection of compressor I is a discharge line 4 which is connected to the bottom ports 5 and 6 of three-way valves 'I and 8 respectively. The left-hand port 9 of three-way valve 'I is connected by a pipe I0 to a heat exchanger II which acts as a condenser when the system is operating on the heating cycle and as an evaporator or water cooler when the system is operating on the cooling cycle. The right-hand port I2 of the three-way valve 8 is connected by a pipe I3 to a heat exchanger I4 which is adapted to act as a condenser for the cooling cycle and as an evaporator for the heating cycle. 'I'he right-hand port I5 of valve I and the left-hand port I6 of valve 8 are connected by pipes I'I and I8 to a trap I9, the upper end of which is connected by a suction line to the inlet of the compressor I.

The heat exchangers II and I4 are indicated diagrammatically as comprising casings enclosing coils 2| and 22 respectively. Leading from the casing of heat exchanger I I is a pipe 23 which is joined to solenoid valves 24 and 25. The valve 24 is connected b-y pipe 26 to a receiver 21. The receiver 2l is also connected by a pipe 28 to a solenoid valve 29 which in turn is connected by a pipe 30 to the casing of heat exchanger I4. The pipe 30 is also connected by pipe 3I to a solenoid valve 32. Valves 25 and 32 are connected by pipe 33, which in turn is connected by pipe 34 to a float switch 35 which is located above the heat exchangers II and I4. This float switch is also connected to a drain pipe 36 which leads from the trap I9.

The valves l, 8, 24, 25, 29 and 32 are controlled by means of a changeover relay indicated generally as 3'I. Referring now to Figure 2, this relay comprises a coil 38 which actuates through a suitable armature, not shown, switch arms 39, 40, 4I, 42 and 43, each of which cooperates with in and out contacts as shown. When the coil 38 is energized, the various switch arms are brought into engagement with their respective in contacts and when the coil 38 is deenergized the switch arms are moved under the action of springs or gravity, not shown, into engagement with their respective out" contacts. The relay 3l is controlled in a manner which will be hereinafter described for causing the switch arms to engage their in contacts when outside temperature is at or above and for causing the switch arms to engage their out contacts when outdoor temperature falls below 70.

Thethree-way valves 'I and 8 are each provided with three terminals a, b and c. These valves are arranged so as to place their lower ports into communication with their left-hand ports when power is supplied to terminals a and b, while causing their left and right hand ports to be placed into communication when power is supplied through terminals b and c. Valves of this general type are well-known in the art and no further description is necessary. The solenoid valves 24, 25, 29 and 32 are each of the type which opens when energized and which closes when deenergized.

The valves 1, 8, 25 and 32 are controlled by means of the switch arm 48 of relay7 31. Referring now to the wiring connections, reference character 44 indicates a step-down transformer having a secondary 45. One side of this secondary 45 is connected by wires 46, 41, 48, 49, 50, 5I and 52 to the valves 1, 8, 25 and. 32. The other terminal of transformer secondary 45 is connected by Wires 53 and 54 to the switch arm 48. When the switch arm 40 engages its in contact, a circuit is completed from transformer secondary 53 through wire 54, switch arm 40, wire 55, wire 56 and wire 51 to terminal c of the threeway valve 1 which causes this valve to assume a position for placing its ports 9 and I5 into communication. Also, at the sametime a parallel circuit is completed from wire 56 to terminal a of three-way valve 8 by wire 58, which causes this valve to assume a position in which its ports 6 and I2 are placed into communication. In addition, when the switch arm 40 engages its in contact another parallel circuit is completed from wire 55 through wire 59 to valve 25, which causes this valve to open.

The solenoid Valves 24 and 29 are controlled by means of the float switch 35 and the switch arm 4I of relay 31. When the switch arm 4I engages its in contact a circuit is completed from transformer secondary 45, wire 53, wire 54, wire 6U, switch arm 4I, wire 6|, wire 62 through valve 29, wire 63, wire 64 and wire 46 back to transformer secondary 45. This energization of the valve 29 causes this valve to remain open. The oat switch 35 is connected by wire 66 to the junction of wires 6I and 62 and is also connected by wire 65 to the junction of wires 61 and 68, the wire 61 leading to valve 24 and Wire 68 leading to the out contact cooperating with switch arm 4| of relay 31. When the refrigerant level within float switch 31 falls too low, this switch will close which will complete a circuit from Wire 6I through wire 66, oat switch 35 and wire 61 to valve 24 for causing this Valve to open. However, when the liquid level within float switch 35 rises to a predetermined level, the switch 35 will` open for breaking the energizing circuit to valve 24 thus permitting this valve to close.

Referring again to Figure 1, when the valves 1 and 8 are in the positions shown in Figure 2, compressed refrigerant will pass from the compressor through discharge line 4 into port 6 of three-way valve 8 and out through port I2 of this valve and through the pipe I3 to the heat exchanger I4 which, at this time, acts as a con-4 denser for condensing the compressed refrigerant. At this time the valve 29 is continuously open as previously described, which permits the liquid refrigerant to flow through pipes 38 and 28 into the receiver 21 from which it flows through pipe 26 to the valve 24. This valve is at present under the control of the oat switch 35 which is now connected so as to respond to the level of refrigerant within heat exchanger II,

due to valve 25 being open and valve 32 being closed. The iioat switch 35 will therefore control the valve 24 in a manner to maintain the predetermined refrigerant level. Evaporated refrigerant will now pass from the heat exchanger II through pipe I0 to the port 9 of three-way valve 1 and will leave this valve through port I5, passing through pipe I1 into the trap I9 and from this trap the refrigerant will pass through suction line 20 back to the compressor I. Any liquid refrigerant which is carried over from heat exchanger I I will be separated out in the trap I9 and will flow from this trap through the drain pipe 36 to the float switch 35 and from this switch through pipe 34 back into heat exchanger I I.

From the foregoing description it should be apparent that when the-relay 31 is energized, the three-way valves 1 and 8 will be positioned for causing refrigerant to flow first through the heat exchanger I4, which acts as a condenser, and then through the heat exchanger I I which acts as an evaporator or water cooler. At this time the valves 25 and 32 will be positioned for causing `the float switch 35 to respond to the liquid-,level in heat exchanger II and this float switch will be placed into control of solenoid valve 24, the Valve 29 being held wide open continuously at this time.

When the changeover relay 31 is deenergized for causing the system to operate on the heating cycle, the switch arms 40 and 4I will disengage their in contacts and engage their out contacts. Disengagement of switch arm 48 from its in contact will deenergize the solenoid valve 25 for causing this valve to close. Engagement of the switch arm 40 with its out Contact will complete a circuit from transformer secondary 45 through wire 53, wire 54, switch arm 40, wire 1I), and wire 1I to valve 32 for opening this valve. Also a parallel circuit will be completed from wire 10 through wires 12, 13 and 14 to terminal a, of valve 1 and terminal c of Valve 8 for causing valve 1 to assume a position placing its ports 5 and 9 into communication and for causing valve 8 to assume a position placing its ports I2 and I6 into communication.

Due to disengagement of switch arm 4I from its in contact, the continuous energization of valve 29 will be interrupted and due to engagement of this switch arm with its out contact a circuit will be completed for continuously energizing valve 24 as follows: transformer secondary 45, wire 53, wire 54, wire 68, switch arm 4I, wire 68, wire 61, valve 24, wire 63, wire 64, and wire 46 to secondary 45. At this time the float switch 35 will be capable of energizing valve 29 by completing a parallel circuit from wire 68 through wires 65, 66 and 62 to valve 29. Thus when the relay 31 is deenergized, the valve 24 is held open continuously and valve 29 is placed under control of the float switch 35.

Referring again to Figure l, with the valves in the positions just described due to relay 31 being deenergized, refrigerant will flow from the compressor I through discharge line 4 into Valve 1 leaving this valve through port 9 and passing through pipe I6 into the heat exchanger II, which will now act as a condenser. Liquid refrigerant will now pass through valve 24, which is continuously held open, into the receiver 21 and through the valve 29 which is now controlled by float switch 35, into the heat exchanger I4 which acts as an evaporator. At this time the valve 25 is closed and the valve 32 is open for causing the float switch 35 to respond to the level of the liquid refrigerant in heat exchanger I4. Evaporated refrigerant will now pass from heat exchanger I4 through pipe I3 to valve 8, leaving this valve through port I6 and passing through pipe I8 into the trap I9 from which it passes through suction line 20 to the compressor I.

From the foregoing description it should now be obvious that when the relay 31 is energized the heat exchanger I4 will operate as a condenser and the heat exchanger II will operate as an evaporator. However, when the relay 31 is deenergized, the heat exchanger I| will operate as a condenser and the heat exchanger I4 will operate as an evaporator.

Reference character 15 indicates an air conditioning chamber which may he supplied with fresh air or with a mixture of fresh air and return air withdrawn from the space being conditioned. The chamber 15 is connected to a fan 16 which draws air through the chamber 15 and discharges it through a discharge duct 11 into the space 18 being conditioned. Located in the chamber 15 is a heat exchange coil 19 which operates as a precooler for the air when the` Thus when pump 8| is in operation, well water is passed into the coil 19 and passes from this coil through a pipe 86 which leads to the inlet of a reheater coil 81, and from this coil passes through pipe 88 to a valve 89 and through this valve and pipe 90 to the coil 22 in the heat exchanger I4. The water leaves this coil 22 through pipe 9| and passes through a valve 92 and pipe 93 to a sump 94 which may be connected by means of a subterranean ditch 95 with the well 85. During normal operation of the system on the cooling cycle, the Water withdrawn from well 85 is cooler than the air supplied to conditioning chamber 15 and in passing through the heat exchanger 19 in counter-flow relation with the air, causes the air temperature to be reduced. Due to the counter-flow heat exchange relationship, the temperature of the water leaving coil 19 will be higher than the temperature of the air leaving this coil and consequently this water may be utilized for providing reheat if necessary. It will be noted that a by-pass valve 96 is provided around the reheater 81, this valve being controlled by a thermostat 91, the control bulb 98 of which is located in the discharge duct 11 so as to respond to the temperature of the air being discharged to the space 18. If the temperature of the discharged air falls below a predetermined value, the thermostat 91 will cause the valve 96 to be closed which forces the water through the reheater 81 before passing to the heat exchanger I4 for condensing the refrigerant. However, when the discharge air temperature is above the setting of thermostat 91, the valve 96 is caused to open for thus permitting the water to by-pass the reheater 81.

When the system is operating on the heating cycle, the temperature of the well water will be higher than the temperature of the air supplied to the conditioning chamber 15, which renders the well water available as a medium for preheating the air. At this time, due to operation of the system for heating, the temperature of the discharge air will be always above the setting of thermostat 91 which causes this thermostat to maintain valve 96 open. This permits the heating water to pass from the well through the coil 19 which acts as a preheater, directly to the heat exchanger I4, and from this heat exchanger to the sump 94. Therefore, during the heating cycle the coil 81 is always out of operation for preventing it from cooling down the heated air.

Reference character |00 indicates a circulating pump which is driven by means of an electric motor IOI having a starter |02. The inlet of this pump is connected by pipe |03 to the coil 2| in heat exchanger II, and the discharge of this pump is connected by pipe |04 to a valve |05. The outlet of the valve |05 is connected by pipes |06 and |01 to the storage tank |01a which is in turn connected to coil |08 located in conditioning chamber 15. The coil |08 is adapted to act as a heater during the heating cycle and as a cooler during the cooling cycle. The storage tank |01a may also be provided with a by-pass |01b containing a solenoid valve |010 which is responsive to the temperature of the Water leaving storage tank |01a. This valve I01c is controlled by a thermostat I01d, responsive to the temperature of the water leaving tank I01a. This thermostat controls the valve |01c in a manner to close this valve when the water leaving tank |01a is either suliciently hot for heating, or suiiiciently cool for cooling. Whenever the water temperature is at an intermediate value, the thermostat I01d will cause valve I01c to open for thus bypassing the water directly to the cooling coil |08. The outlet of coil |08 is connected by pipe |09 to the inlet of coil 2| in heat exchanger I I. It will be apparent that the pump |00 acts to circulate water or other heat exchange medium between the coil 2| in heat exchanger |I and the coil |08 in conditioning chamber 15, the storage tank |01a providing for storage of hot or cold heat exchange medium. The heat exchanger II, it will be remembered, operates as an evaporator or water cooler during the cooling cycle and as a condenser or water heater during the heating cycle. The arrangement just described, therefore, acts to cause cold water to be supplied to coil |08 when the system is operating for cooling and to supply hot water to this coil when the system is operating on the heating cycle.

From the description thus far, it should be apparent that coil |08 forms the primary heat exchange surface in conditioning chamber 15 and operates to cool the air in summer and to heat the air in winter due to the reversing arrangement of the refrigeration system, which causes the heat exchanger |I to operate as a condenser in winter and as an evaporator in summer. It should also be apparent that the heat exchange coil 19 operates either as a precooler or as a preheater for the air being passed to the coil |08. Also it should be noted that the heat exchanger coil 19 acts to utilize the temperature diiierence between the well water and the air supplied to the conditioning chamber for providing either the precooling or reheating, and then supplies this Water to the heat exchanger I4. Consequently, when the system operates on the cooling cycle the well water is utilized for precooling the air and then for cooling the condenser, thus making maximum use of this well water and increasing the system erliciency. Also, when the system operates on the heating cycle, the heat exchanger I4 acts as an evaporator and the welll water in passing through this heat exchanger acts as a source of heat for the reversible cycle system.

Reference character indicates generally a step controller which is controlled by means of a thermostat II| which has its control bulb ||2 located in any suitable manner so as to be responsive to outside temperature. This control bulb ||2 is preferably provided with a shield I |2a ReferrigwtdFigure 2, the step controller I l0 comprises an electric proportioning motor I I3 having an operating shaft |I4 which actuates cams II5, I|6 and ||1. The proportioning motor ||3 is preferably of the type shown in the Taylor Patent 2,028,110 and is adapted to be controlled by a potentiometer controller in a manner to cause its operating shaft to assume angular positions corresponding to the position of a potentiometer slider upon its resistance.

The thermostat III is a potentiometer type thermostat and may consist of a bellows |I8 which is connected to the control bulb ||2 for causing the pressure within this bellows to vary in accordance with outside temperature. The bellows ||8 actuates a bell crank lever having an actuating arm ||9 and a control arm |20 which cooperates with a resistance I2| to form a control potentiometer. The actuating arm ||9 may be biased against the bellows ||8 by a spring |22 as shown. This instrument may be so designed and adjusted as to cause the slider |20 to engage the left-hand end of resistance I2I when outdoor temperature falls to 60 F. or below, while causing the slider |20 to engage the right-hand end of resistance |2| when outdoor temperature rises to 90 F. or above.

With the thermostat parts in the position shown, the outdoor temperature is at or above 90 F. as indicated by the slider |20 engaging the right-hand end of resistance |2|. This has caused the proportioning motor ||3 to rotate its shaft I |4 to its clockwise limit of rotation. Upon fall in outdoor temperature the slider |20 will begin moving to the left across resistance |2I and this movement will be followed up by corresponding counter-clockwise rotation of the motor shaft II4. Thus when outside temperature falls to 60 F. or below, the shaft ||4 will assume its counter-clockwise limit of rotation.

The cam II actuates cam follower |23, which carries a mercury switch |24. This cam is provided with a recessed portion |25 which corresponds to F. and the cam is mounted upon the shaft I|4 in a manner to cause this recessed portion to engage the cam follower when outdoor temperature is between 60 F. and '10 F. By this arrangement, when outdoor temperature is between 60 F. and 70 F. the mercury switch |24 is tilted to open position. The mercury switch |24 controls the pump motor starter 83. This starter may be of usual form andis illustrated as comprising a coil |26 for actuating switch arms |21, |28 and |23 which are connected between a source of power and the pump motor 82. When the mercury switch |24 is closed, a circuit is completed from line wire |30 through coil |26, wire |32, mercury switch |24 and wire |33 to line wire |34, thus causing switch arms |21, |28 and |29 to engage their respective contacts for completing the power circuit to pump motor 82. When mercury switch |24 is open the energizing circuit for coil |26 will be broken, thus causing the switch arms to disengage their contacts for placing the pump out of operation. It should thus be apparent that the pump 8| will be in operation whenever outside temperature is below F. or above F. and will be out of operation when outside temperature is between these values.

The cam ||6 actuates a cam follower carrying a mercury switch |35, which controls the pump starter |02 for the pump motor 0|. The cam ||6 is provided with a recessed portion corresponding to 10 F. of rotation of motor shaft |I4, and is located on this shaft so that its recessed portion engages the cam follower when outside temperature is between '70 F. and 80 F. This arrangement causes the pump |00 to be in operaltion whenever outside temperature is below 70 F. or above F. while placing this pump out of operation when outside temperature is between these values.

The cam ||1 actuates a mercury switch |35 which is connected to control the changeover relay 31. The cam ||1 is arranged to tilt mercury switch |36 to open position when outdoor temperature falls to '10 or below while causing this switch to be closed when outside temperature is above 70 F. When mercury switch |36 is closed, a circuit will be completed from transformer secondary 45, wire 53, wire |31, mercury switch |36, wire |38, relay coil 38 and wire |39 back to secondary 45. This will cause coil 38 to be energized for thus positioning the relay switch arms for placing the system on the cooling cycle. When the mercury switch |36 is open, the relay 31 will be deenergized for placing the system on the heating cycle.

From the above description it will be seen that the thermostat I I operates through the step controller |I0 in a manner to place the pump 8| out of operation when outdoor temperature is between 60 F. and 10 F., to place the pump |00 out of operation when outside temperature is between '10o F. and 80 F. and toposition the changeover relay 31 for operating the system on the cooling cycle when outside temperature is above 70 F. and for operating the system on the lqieating cycle when outside temperature is below Referring now to the controls for compressor I, the variable speed motor 2 therefor is provided with a speed control box 3 having a common control terminal I40, a high speed control terminal I 4I, an intermediate speed terminal |42 and a low speed terminal |43. This speed control box is controlled by means of a step controller generally indicated as |44. This step controller |44 may comprise a proportioning motor |45 which also may be of the type shown in the Taylor patent. This motor |45 is provided with an operating shaft |46 upon which are mounted cams |41, |48 and |49. The cam |41 actuates a mercury switch |50, the cam |48 actuates a mercury switch I5I and the cam |49 actuates a mercury switch |52. The cams |41, |48 and |49 are differentially adjusted on shaft |46 in a manner to cause the switches |50, |5| and |52 to close in sequence upon rotation of shaft |46 in a clockwise direction. Upon rotation of shaft |46 in the opposite direction the switches will be opened in inverse order.

The common terminal |40 of control boX 3 is connected by wire |53 to each of the mercury switches. The low speed terminal |43 of this control box is connected by wire |56 to mercury switch |52. Consequently, when only switch |52 is closed the compressor will operate at low speed. The intermediate speed terminal |42 is connected by wire |55 to mercury switch |5I, and the high speed terminal 4| is connected by wire |54 to mercury switch |52. By this arrangement, when shaft |45 is at its counter-clockwise limit of rotation the switches |50, |5| and |52 will all be open, which will cause the compressor I to be out of operation. As shaft |46 rotates in a clockwise direction the mercury switch |52 will rst be closed for causing the compressor to operate at low speed. Upon further rotation of shaft |46 in the same direction, switch |5| will close for causing operation of the compressor at intermediate speed and upon still further rotation the switch |50 will close for operating the compressor at high speed. The arrangement just described, therefore, places the compressor out of operation or operates it at either low, intermediate or high speed depending upon the angular position of the motor shaft |46.

The proportioning motor |45 for the step controller |44 is controlled primarily by means of a space thermostatic device |60, and this thermostatic device is reversed in operation for summer and winter operation by means of the changeover relay 31. The proportioning motor |45 is also controlled by means of a limit controller 6| which may take the form of a step controller controlled by a thermostat |52 which is responsive to the temperature of the water leaving heat exchanger this controller in turn being in eiect adjusted by means of a potentiometer actuated by the step controller ||0. The step controller motor |45 is additionally controlled by means of a high pressure cut-out |63 and a low pressure cut-out |64.

Referring to the high pressure cut-out |63, this controller may be of usual form and comprises a bellows |65 which is attached to the discharge line 4. This bellows actuates a switch carrier |66 carrying a double pole type mercury switch |61. The switch carrier |66 is biased against the action of bellows |65 by a spring |68. So long as the discharge pressure is not excessive, the spring |68 will maintain the switch carrier |66 in the position shown for bridging the righthand electrodes of mercury switch |61. However, when the discharge pressure becomes excessive due to failure of cooling water supply to the condenser or for other reasons, the bellows |65 will expand against the action of spring |68 for unbridging the right-hand electrodes of switch |61 and bridging the left-hand electrodes thereof. The low pressure cut-out |64 may be of similar construction to the high pressure cut-out |63 but this controller is arranged to cause bridging of the left-hand electrodes of mercury switch |69 when the suction pressure is above a predetermined value. When, however, the suction pressure falls to the predetermined low Value, the switch |69 will be tilted for bridging its righthand electrodes.

The limit controller |6| consists of a potentiometer including a slider |10 and a resistance |1| The slider |10 is actuated by means of a proportioning motor |12 which may be of the type shown and described in the Taylor Patent 2,028,110. This proportioning motor |12 is controlled by the thermostat |62 which is responsive to the temperature of the water leaving the heat exchanger This thermostat is diagrammatically illustrated as ccnsisting of a bellows |13 which actuates a lever assembly including an actuating arm |14, a control arm or slider |15 and a corrector arm |16. The control arm |15 cooperates with a control resistance |16 to form a potentiometer controller, and the corrector arm CII 10 to the left across resistance |1|.

|16 engages a center tapped resistance |18 for correcting the action of the controller. The bellows |13 is connected by a capillary tube to a control bulb |19 located on the pipe |03 (Figure 1). Upon a decrease in temperature of water leaving the heat exchanger the pressure within bellows |13 will decrease thus permitting a biasing spring to rotate the arms |15 and |16 in a counter-clockwise direction across their respective resistances, while upon an increase in temperature the arms |15 and |16 will be shifted in the opposite direction. This instrument may be so designed and adjusted as to cause the slider |15 to engage the right-hand end of resistance |11 when the water temperature is at 60 F. or above, while engaging the left-hand end of said resistance when the water temperature falls to 45 F.

The proportioning motor |12 is also controlled by means of a compensating potentiometer |8| which is actuated by the step controller |0. This compensating potentiometer consists of a slider |82 actuated by the shaft ||4 and which cooperates with a resistance |83. This resistance is arranged with respect to the slider |82 in a manner to cause slider |82 to engage the lower end of said resistance when outside temperature is at 90 F. or above, while engaging the upper end of said resistance when outside temperature falls to '70 F. The resistance |83 at its upper end is attached to a contact segment |84 upon which the slider |82 rides when the outside ternperature falls below 70 F.

Upon reference to the Taylor Patent 2,028,110, itfwill be found that the proportioning motor |12 is provided with three control terminals which in the drawings are marked R, 'W and B. This motor is adapted to assume intermediate positions within its range of rotation depending upon the relative values of resistance connected between terminals R and W and between terminals R and B. For instance, if equal values of resistance are connected across these terminals, the motor will assume intermediate positions at which the slider 10 engages the center of resistance |1|. If the resistance between terminals R and W is decreased without corresponding decrease in resistance between terminals R and B, the motor will rotate in a direction for shifting slider |10 to the right across resistance |1|. Also if the resistance between terminals R and B is decreased without corresponding decrease in resistance between terminals R and W, the motor |12 will rotate in a direction for shifting slider Terminal R is connected by wires |85 and |86 to the resistance |18. As the sliders |15 and |16 are connected together, the slider |15 is therefore connected to terminal R. The terminal W of motor |12 is connected by wire |81 to the right-hand end of resistance 11 and terminal B of this motor is connected by wires |88 and |89 to the left-hand end cf resistance |11. With the thermostat |62 in the position shown, the water temperature is at 60 F. or above as indicated by the slider |15 engaging the right-hand end of resistance |11. This places the entire resistance |11 between terminals R and B of motor |12 and completes a substantial short-circuit between terminals R and W of this motor. This degree of unbalancing of resistance between terminals R and B and R and W of motor |12 causes this motor to assume a position in which the slider |10 engages the right-hand end of resistance |1| Upon a decrease in temperature of the water leaving heat exchanger the slider |15 will begin moving to the left across resistance |11 thereby inserting a portion of this resistance between terminals R and W and removing this same portion from the circuit between terminals R and B. This will cause the motor |12 to shift the slider to the left across resistance |1| in proportion to the movement of the slider on resistance |11,

The slider |82 of potentiometer |8| is connected to terminal R of motor |12 by wires |85, |90, rheostat |9| and wire |92. The lower end of resistance |83 is connected by wires |93 and |88 to terminal B of motor |12, and terminal W of this motor is connected to the upper end of resistance |83 by wires |81 and |94, and the contact segment |84. The potentiometer I8| is therefore connected in parallel with the potentiometer of thermostat |62 into the control circuit of the motor 12. When the outdoor temperature is at 90 or above, the slider |82 engages the lower end of resistance |83 which places the entire resistance 83 between terminals R and W of motor |12 and tends to short-circuit terminals R and B but for the action of the rheostat |9|. This rheostat, however, limits the current flow through the slider |82 and thus causes the potentiometer |8| to have less effect upon the motor |12 than the potentiometer of thermostat |62. It will be noted that when outdoor temperature is at 90 or above, the tendency of potentiometer |8| is to shortcircuit terminals R and B thus tending to cause motor' |12 to shift slider |10 to the left across resistance |1|. As the slider |82 moves upwardly across resistance |83 due to decreasing outside temperature, the portion of resistance |83 which is connected between terminals R and W is decreased and this portion is simultaneously placed into circuit between terminals R and B for tending to cause motor |12 to shift slider |10 to the right on resistance I1 It will thus be apparent that the action of the slider |8| upon falling outside temperature is opposite to the eifect of thermostat |62 upon fall in cooling water temperature. The potentiometer |8| thus in effect acts to change the relationship between thermostat |62 and motor |12. In other words, as the outdoor temperature increases, the slider |15 of thermostat |62 must move further to the right to maintain slider |10 at the right-hand end of resistance |1i. The potentiometer 8| therefore provides an adjustment for the thermostat I 62 and acts to raise the controlV point of this thermostat upon increase in outside temperature and to lower the control point of this thermostat upon decrease in outside temperature. The specic control arrangement of motor |12 forms no part of this invention and for further details of this arrangement reference is made to the application of John E. Haines, Serial No. 38,946 led September 3. 1935. The purpose of this adjustable limit controller |6| is to limit the minimum water temperature when the system is operating on the cooling cycle to prevent this water from being chilled more than necessary for cooling the space, thereby providing for operating the system at maximum economy. As the outside temperature increases, the control point of this limit controller is raised so as to cause the minimum cooling water temperature to rise upon increase in outside temperature.

The space thermostat |60 really comprises two separate thermostats 200 and The thermostat 200 may include a bellows 202 which actuates a bell crank lever including a slider 203 which 75 cooperates with a resistance 204 to form a control potentiometer. The thermostat 200 is for controlling the system when operating upon the cooling cycle, and this thermostat may be arranged to cause the slider 203 to engage the lefthand end of resistance 204 when the space temperature rises to 80 F. while causing the slider 203 to engage the right-hand end of resistance 204 when the space temperature falls to 75 F. The thermostat 20| is for controlling the system on the heating cycle and is arranged to operate reversely from the thermostat 200. This thermostat includes a slider 204 which cooperates with a resistance 205 and may be so designed and adjusted as to cause the slider 204 to engage the right-hand end of resistance 285 when space temperature is at or above 72 F. while engaging the left-hand end of this resistance when the space temperature falls to F.

Referring now to the wiring between these controllers, it will be noted that terminal B of motor |45 is connected by wires 206 and 201 to the left-hand ends of resistances 204 and 205, and that terminal W of this motor is connected to the right-hand ends of these resistances by wires 208, 209, 2|0 and 2||. Assuming now that the high and low pressure cut-outs |63 and |64, are in normal position, that the slider |10 orf-limit controller |6| is engaging the right-handend of resistance |1|, and that the changeover relay 31 is energized, terminal R will be connected to the slider 203 of thermostat 200 as follows: terminal R, wire 2| 2, right-hand electrodes of mercury switch |61, wire 2|3, left-hand electrodes of mercury switch |69, wire 2|4, slider |10, wire 2|5, switch arm 39, and Wire 2|6 to the slider 203. The space thermostat 200 is therefore in control of the proportioning motor |45. In the position shown, the space temperature is at 80 F., which has caused the slider 203 to engagethe left-hand end of resistance 204 which places the entire resistance 204 between terminals R and W of motor |45 and substantially short-circuits terminals R and B. This has caused motor |45 to assume its extreme clockwise limit of rotation, which causes operation of the compressor at full speed in the manner previously described. As the space temperature decreases, the slider 203 will shift to the right across resistance 204 and in response to this movement the motor |45 will rotate counter-clockwise, which will,.first tilt mercury switch |50 of step controller |44 to open position, thus descreasing the compressor speed from high speed to intermediate speed. Upon further decrease in space temperature, the thermostat 200 will cause the step controller motor |45 to rotate further in a counter-clockwise direction for decreasing the compressor speed. When the space temperature falls to 75 F. the proportioning motor |45 will assume its counterclockwise limit of rotation for causing the compressor to be placed out of operation.

Te above description assumes that the compressor speed called for by the room thermostat is not sucient to chill the water to the setting of the low limit controller |8I. In the event that the cold water temperature falls below the setting of this limit controller, the slider |10 will be shifted to the left across resistance |1| in the manner` previously described. This will insert a portion of resistance 1| into the circuit between terminal R and motor |45 and the slider 203 of thermostat 200, thus decreasing the effect of this thermostat upon motor |45. At this time it should be noted that the left-hand end of resistance |1| is connected by wires 2|8, 209 and 208 to terminal W of motor |45. Thus at the time that slider |10 engaged the right-hand end of resistance |1|, this entire resistance was connected between terminals R and W. This shifting of the slider |10 to the left across resistance |1| thus in addition to inserting a portion of this resistance in circuit with the slider 203, also decreases the portion of this resistance in circuit between terminals R and W which causes rotation of this motor in a direction to decrease the compressor speed. The limit controller |6| therefore prevents the thermostat 200 from operating the compressor at a speed which will cool the water lower than necessary. As pointed out above, the control point of the limit controller is Varied in accordance with outside temperature, thereby insuring that the cooling water temperature is raised in proportion to rise in outside temperature, thereby preventing an excessive and uneconomical temperature difference between the cooling water and the air being cooled.

In the event of the head pressure becoming excessive, the high pressure cut-out |63 will operate to unbridge the right-hand electrodes of mercury switch |61 and to bridge the left-hand electrodes thereof. This will complete a shortcircuit through wires 2|2, 2|9 and 208 between terminals R and W of motor |45 for causing it to operate for placing the compressor out of operation. Similarly, if the suction pressure falls below a predetermined value the suction pressure controller |64 will operate to unbridge the lefthand electrodes of mercury switch |69 and to bridge the right-hand electrodes thereof, which will short-circuit terminals R and W of motor |45 as follows: terminal R, wire 2|2, right-hand electrodes of mercury switch |61, wire 2|3, righthand electrodes of mercury switch |69, wire 220 and wire 208 to terminal W. Therefore, if either the high pressure rises too high or the suction pressure falls below a predetermined value the compressor will be placed out of operation.

When the relay 31 is deenergized for causing changeover of the system from the cooling cycle to the heating cycle, the switch arm 39 will disengage its in contact and engage its out contact. Disengagement of the switch arm 39 from its in contact will break the circuit between terminal R of motor |45 and slider 203 of thermostat 200, thereby placing this thermostat out of control of the compressor. Engagement of the switch arm 39 with its out contact will complete a circuit from terminal R of motor |45 to the slider 204 of thermostat 20| as follows: terminal R, wire 2 I2, right-hand electrodes of Inercury switch |61, wire 2|3, left-hand electrodes of mercury switch |69, wire 2|4, slider |10, wire 2|5 switch arm 39 and Wire 222 to slider 204. The winter thermostat 20| will therefore be placed in control of the compressor and this thermostat will operate to increase the speed of the compressor upon fall in temperature and to decrease the compressor speed upon rise in temperature in a manner to maintain the space temperature between '10 F. and '12 F. At this time, the heat exchanger will be operating to heat the water passing therethrough and consequently the temperature of this water will always be above the setting of ylimit controller |6I, thus causing the slider |10 to remain engaged with the right-hand end of resistance |1|. The limit controller |6| therefore does not affect the control of the compressor by the winter thermostat 20|. It should be noted that a resistance 225 is connected between terminals B and R of motor |45. This resistance should be equal in value to resistance I1| and is provided for the purpose of balancing this resistance in the control circuit.

From the foregoing description it should be apparent that the control of the compressor speed controller is shifted from thermostat 200 to the thermostat 20| and vice versa by the changeover relay 31, and that the thermostat 20| acts to control the compressor during the cooling cycle while the thermostat 20| controls the compressor on the heating cycle. It also should be seen that the limit controller |6| will act to limit the minimum temperature of the cooling water during the cooling cycle and that this minimum or low limit temperature is determined in accordance with outside temperature. During the heating cycle this low limit controller is satisiied and consequently does not affect the control of the compressor by the winter thermostat 20|. Also at any time if the discharge pressure rises too high or the suction pressure falls too low, the compressor will be placed out of operation.

This invention also contemplates the heating of domestic water by the air conditioning system both when it is in operation on the cooling cycle and 0n the heating cycle. This arrangement will now be described in detail. In Figure 1, reference character 230 indicates a storage tank for domestic hot water and this tank is provided with a discharge pipe 23| for conveying water to the points of use. This tank is provided with an inlet pipe 232 for conveying heated water thereto. This pipe 232 is connected to a pipe 233 which leads from the pipe |06 in the circulation circuit between heat exchanger and coil |08. Pipe 232 is also connected to pipe 234 which leads from the pipe 9| at the outlet of coil 22 in heat exchanger I4. This pipe 234 is provided with a check valve 235. Reference character 236 indicates a pipe leading from a source of water such as a city water service line, and this pipe is connected to pipe 231 which is connected to the pipe 99 which leads to the coil 22. Interposed in pipe 231 is a motorized valve 238 including a proportioning motor 239. The pipe 236 is also connected by a pipe 240 to the pipe |09 which leads from coil |08 to the coil 2| in heat exchanger This pipe 240 has interposed therein a solenoid valve 24|. The valves 238 and 24| are controlled by means of the changeover relay 31 and a pressure controller 242 which `is responsive to the pressure in tank 230. The valves 89 and 92 and the by-pass valve 244 are also controlled by relay 31 and the pressure controller 242 through a relay device 245. The valve 238 is additionally controlled by means of a thermostat 241 which is responsive to the temperature of the water flowing to tank 230 through the pipe 232.

Referring now to Figure 2, these controls will be described. The pressure controller 242 may be of usual form and consists of a bellows 250 which is connected by a tube 25| to the air space within tank 230. This bellows operates a mercury switch carrier carrying mercury switch 252 and is arranged to tilt this switch to open position when the pressure within tank 242 is at the desired value, while tilting this switch to closed position when the pressure falls to a predetermined lower value.

The relay device 245 contains a rst relay 253 which consists of a relay coil 254 which operates through a suitable armature a pair of switch arms 255 and 256, each of which is provided with in and out contacts as shown. When coil .,.iLQ-lirneagenigllrimligaigagas 26| insnlldese-ambimetallicaelerngpt 254 is energized the switch arms 255 and 256 engage their respective in contacts, and when coil 254 is deenergized these switch arms engage their out contacts. Also included within the relay device 245 is a second relay 251 having a coil 258 for operating through a suitable armature a switch arm 259 which cooperate with a contact 268. The device 245 also includes iggzillm.Qmelegzs r'luhis timer ,"il'miyswr ranged to be heated by means of an electric heating element 263. The element 262 is xedly secured at its upper end and at its lower end carries a contact adapted to cooperate with a contact 264. When the element 263 is deenergized, the bimetallic element 262 will be cooled which will cause it to assume the position shown in which its contact is in engagement with contact 264. However, when the element 263 is energized, the bimetallic element will be slowly heated and after a predetermined interval of time, this element will warp to the right for disengaging from contact 264.

The thermostat 241 is of the potentiometer type and includes a slider 265 which cooperates with a resistance 266. The bellows 261 of this thermostat is connected by a capillary tube to the control bulb 268 which is located on pipe 234 so as to respond to the temperature of the heated n water owing from the coil 22 in heat exchanger I4 to the tank 230. This thermostat may be designed and adjusted in a manner to cause the slider 265 to engage the right-hand end of resistance 266 when the water temperature is at 130 F. or below, while engaging the left-hand end of said resistance when the water temperature rises to 140 F. The valve motor 239 for the valve 238 is of the proportioning type and is controlled by the thermostat 241 and by the switch arm 256 of relay 254. Terminal R of motor 239 is connected by wire 210 to the switch arm 256, and terminal W of this motor is connected by wire 21| to the out contact of relay 253. Thus when relay 253 is deenergized, terminals R and W of motor 239 are short-circuited for causing this motor to close valve 238 completely. When relay 253 is energized, the switch arm 256 engages its in contact which will complete a circuit from terminal R of motor 239 to the slider 265 of thermostat 41 as follows: terminal R, wire 210, switch arm 256 and wire 212 to slider 265. It will be noted that the right-hand end of resistance 266 is connected to terminal W of motor 239 by wire 213, rheostat 214 and wire 21|, while the left-hand end of this resistance is connected to terminal B by wire 215. Thus when the relay 254 is energized, the valve 238 is placed under the control of thermostat 241. When the temperature of the delivered water is at 130 F. or

below, the slider 265 engages the right-hand end of resistance 266 thus interposing the entireresistance 266 between terminals R and B of the motor, while substantially short-circuiting terminals R and W except for the resistance of the rheostat 214. Due to this resistance interposed in the circuit by rheostat 214, the valve 238 is prevented from closing entirely for thus providing a minimum flow of water through this valve. As the water temperature increases, the slider 265 moves to the left across resistance 266 thus opening valve 238 wider in proportion to the rise in water temperature. Therefore when the relay 253 is deenergized, the valve 238 is completely closed, while when this relay is energized, this valve is opened under the control of thermosta 241 and is modulated from a minimum open position to wide open position in accordance with the temperature of the water being delivered to the tank 230.

Due to the relay 31 being energized, the sys- "tem is placed in condition for operating on the cooling cycle. At this time the relay 253 is deenergized which causes the valve 238 to be entirely closed. Due to the switch arm 255 engaging its out contact, the valve 89 is energized as follows: from secondary 216 of transformer 211, wire 218, wire 219, switch arm 255, wire 280, valve 89, wire 28|, wire 282 and wire 283 to secondary 216. The valve 89 is therefore open, wil lfsgfhizdnue:jo errno-electric timer Wc911- tactsleiiig closed: A b" szitrgiztrilr from transformer secondary 216, wire 218, wire 219, wire 284, element 262, Contact 264, wire 285, 'valve 92, wire 289, wire 281, wire 282 and wire 283 vto secondary 216. The Valve 244 at this time is `deenergized and therefore closed. Therefore, with the parts in the position shown the system' is operating on the cooling cycle thus causing vthe heat exchanger I4 to act as a condenser for the refrigeration system. Also, the pressure within tank 230 is suiciently high, which causes Valves 238 and 244 to be closed while valves 89 and 92 are open. Water is therefore being pumped from the well 84, passing through the coil 19, pipe 88 and valve 89 to the coil 22 in heat exchanger I4, from which it flows through pipe 9|, valve 92 and pipe 93 to the sump 94.

As hot water is withdrawn from the tank 238 the water level therein will fall, which causes the pressure in the air space above the water to reduce. When this pressure falls to a predetermined Value, indicating that the supply of water in tank 23|] requires replenishing, the mercury switch 252 of the pressure controller 242 will tilt to closed position. This will complete a circuit for energizing relay coil 254 as follows: transformer secondary 216, wire 218, wire 281, mercury switch 252, wire 288, switch arm 42, wire 289, relay coil 254, wire 290, wire 29| and wire 283 to secondary 216. Energization of relay 254 will cause switch arm 256 to disengage its out contact and engage its in contact for thus causing' the valve 238 to open under the control of thermostat 241. Disengagement of the switch arm 255 from its out contact will break the energizing circuit for the valve 89, thus allowing this valve to close. This will prevent further flow of water from the coil 19 into the coil 22 of heat exchanger I4. At this time the valve 92 will remain energized by the same circuit as previously described and thus will remain open. Due to the switch arm 255 engaging its in contact, the valve 244 will be energized as follows: transformer secondary 216, wire 218, wire 219, switch arm 255, wire 292, wire 293, valve 244, wire 294, wire 261, wire 282 and wire 283 to secondary 216.

Therefore when the pressure controller 2'42 calls for replenishing of the water supply in tank 239, valve 238y is opened under the control of thermostat 241, valve 89 is closed, valve 244 is opened and valve 92 remains in open position. Due to the closing of valve 89 and opening of Valve 244 the water leaving the coil 19 in conditioning chamber 15 flows directly to the sump 94 instead of through coil 22 to said sump. Due to opening of valve 238 water flows from the source of supply through pipe 236, pipe 231 and valve 238 to pipe 90, flowing through coil 22', pipe 9|, valve 92 and pipe 93 to sump 94. Thus due to the valve 92 remaining open, city Water is passed throughv the coil 22 for flushing out this coil and this flushing water passes into the sump 94.

At the same time that relay 253 is energized for changing the valve positions as above described, an energizing circuit for the heater 263 is completed through the in contact and switch arm 255 as follows: transformer secondary 216, wire 213, wire 219, switch arm 255, wire 292', wire 295, heating coil 263, wire.296, wire 29| and wire 283 to secondary 216. The thermo-electric timer will therefore begin heating and after a predetermined period this heating will become suicient to cause the bimetallic element 262 to disengage its contact from contact 264 which will interrupt the energizing circuit for valve 92 thus permitting this valve to close. At this time the relay 251 is deenergized and consequently this relay will not complete an energizing circuit to the valve 92,. It should therefore be seen that aftera pretermined period of time following the opening of valves 238 and 294 and the closing of valve 89, the Valve 92 Will close. This closure of valve 92 will prevent further flow of water from the coil 22 to the sump 94. The water will therefore be forced from pipe 9| through the pipe 234, check valve 235 and pipe 232 into the tank 230. At this time the thermostat 241 Will graduatingly control the valve 238 in a manner to maintain the temperature of the water passing to the tank above a predetermined value. For instance, if the temperature of the delivered Water begins falling, the thermostat 241 will close valve 231 further, thereby reducing the rate of flow of water through heat exchanger I4 which permits this water to become more highly heated. Conversely, if the water temperature rises the thermcstat 241 Will cause opening of valve 238 for thus increasing the flow of water to thereby prevent the water from becoming overheated.

When the supply of water within tank 230 is replenished, the pressure controller 242 will deenergize the relay 253 for thus causing this relay to reassume the position shown in the drawings.`

Due to engagement of switch arrn 256 with its out contact, the valve 238 Will be completely closed in the manner previously described for preventing further supply of domestic Water. Due to switch arm 255 disengaging its in contact, the by-pass valve 244 will be deenergized thus causing this valve to close. Also due to this same action, the heating element 263 of the timer 26| will be deenergized for thus permitting this timer to reassume the position shown in the drawings. Due to the switch arm 255 engaging its out contact the valve 89 will be opened by the circuit previously traced. Also due to this switch arm 255 engaging its out contact, the relay coil 258 of relay 251 will be energized as follows: transformer secondary 216, wire 218, wire 219, switch arm 255, wire 280, wire 291, relay coil 258, wire 298 and Wire 283 to secondary 216. This will cause the switch arm 259 to engage contact 260 which will energize valve 92 as follows: transformer secondary 216, wire 218, wire 219, switch arm 255, Wire 280, wire 291, contact 260, switch arm 259, wire 299, wire 285, valve 92, wire 286, wire 281, wire 282 and wire 283 to secondary 216. Therefore, when the pressure controller 252 indicates that the supply of water in tank 230 is replenished, valves 238 and 244 are closed and valves 89 and 92 are immediately opened for permitting the Water flowing from coil 19 to flow through the heat exchanger I4 for thus condensing the refrigerant.

It should now be apparent that When the system is operating on the cooling cycle and the supply of water in tank 230 does not require replenishing, the Valves 89 and 92' are open and valve 244 is closed for causing the Water leaving the coil 19 in heat exchanger 15 to flow through the heat exchanger I4 and then into the sump 94. However, when the Water supply requires replenishing the pressure controller 242 energizes the relay 253 of the relay device 245, which opens the valve 238 under the control of thermostat 241 for permitting domestic water to iiow through the coil 22 of heat exchanger I4. Also at this time the valve 89 is closed for preventing water leaving coil 19 from passing through the coil 22, and valve 244 is opened for permitting this water to flow directly to the sump 94. For a predetermined period of time the valve 92' is retained open for thus permitting the incoming domestic water to llush out the coil 22 and the piping in order to insure that clean water is delivered to tank 230. After this timed flushing period the valve 92 is closed, which causes the water passing from coil 22 to flow into the tank 230 and the flow of water is controlled by the thermostat to maintain the temperature of the delivered water at the desired Value. When the pressure controller 242 indicates that the supply of water within tank 230 is sufficient, this controller deenergizes the relay 253 in the relay device 254 which causes immediate closing of the valves 238 and 244 and opening of the valves 89 and 92 for thus restoring the system to normal cooling cycle operation.

Reference character 300 indicates an air cornpressor which is connected by a pipe 30| to the air space above the water in tank 230. This compressor is driven by an electric motor 302 which is controlled by a iioat switch 303 which is responsive to the level of the Water in the tank 230. When this level rises to a predetermined high value the compressor 300 is placed into operation for forcing additional air into the tank 230. This arrangement provides for replenishing the air supply within the tank 230 and hence avoids any possibility of the tank becoming flooded due to loss of air from this tank by leakage or by becoming dissolved in the water. It should therefore be seen that the controllers 242 vand 303 cooperate to maintain a predetermined amount of water within tank 230 at all times, the controller 242 acting to supply water to the tank in accordance with the pressure Within the tank and the controller 303 acting to maintain a predetermined supply of air within the tank so as to render the controller 242 continuously operative.

When the system is operating on the heating cycle, the heat exchanger I4 operates as an evaporator and theheat exchanger I I operates as a condenser. At this time, therefore, it is necessary to utilize the heat exchanger II for heating the domestic water supply. During the heating cycle the relay 31 is deenergized which thus causes the relay 253 of the relay device 245 to be deenergized. This in turn causes the valves 238 and 244 to remain closed and the valves 89 and 92 to remain open. Therefore, during the heating cycle the pressure controller 242 is completely disconnected from the relay device 245 and consequently during the entire heating cycle heat release or underground water will flow directly from the coil 19 through coil 22 of heat exchanger I4 to the sump 94. Due to the switch arm 42 of the changeover relay 31 now engaging its out contact, the pressure controller 242 is placed in control of the solenoid valve 24| which controls the flow of domestic water to the inlet of coil 2| of heat exchanger I I. Now if the pressure within tank 230 falls below the setting of controller 242, the valve 24| will be energized as follows: transformer secondary 216, wire 218, wire 281, mercury switch 252, wire 288, switch arm 42, wire 305, valve 24| and wire 306 to transformer secondary 216. Water will now flow from pipe 236 through pipe 240 and Valve 24| to the inlet of coil 2|. The water will then flow through this coil and become heated, then owing through pipe |03, pump |00, pipe |04, valve |05, pipe |06, pipe 233 and pipe 232 to the tank 230. Due to the action of check valve 235, this water will not flow into the pipe 234 and thus to the sump 94. When the water pressure within tank 230 is restored to the desired Value, the controller 242 will deenergize the valve 24| which will prevent further flow of domestic water to the system.

The valve |05 is provided for the purpose of throttling the flow of water through the coil 2| to thereby maintain the temperature Of the heated water at a Value which is suitable for supply to the tank 230. This valve |05 is actuated by a proportioning motor 3|0 and this proportioning motor is controlled by means of a thermostat 3| I which is responsive to the temperature of the water flowing from the coil 2|. Motor 3|0 is also controlled by the changeover relay 31 and by a thermostat 3I2 which is responsive to the temperature of the water in tank 230.

The thermostat 3| I is of the proportioning type and includes a bellows 3|3 which is connected by a capillary tube to a control bulb 3I4 located on pipe |04. This bellows 3|3 actuates a slider 3I5 which cooperates with a resistance. 3 I 6 to form a control potentiometer. Upon an increase in temperature of the heated water, the slider 3|5 will move to the left across resistance I6 and upon a decrease in water temperature the slider will be shifted in the opposite direction. The thermostat 3 I 2 may consist of a bellows 3 I 1 which is connected by a capillary tube to a control bulb 3|8 located Within tank 230. This bellows 3I1 actuates a mercury switch carrier carrying a mercury switch 3|9 in a manner to cause the righthand electrodes of this thermostat to be bridged when the temperature within tank 230 is below a predeterminedv value, and to cause bridging of the left-hand electrodes of this switch when the storage water temperature is above such value.

Referring now to the wiring between valve motor 3 I0, thermostats 3| I and 3I2, and relay 31, it willbe noted that terminal R of motor 3|0 is connected by wire 320 to the common electrodes of mercury switch 3I9, while the left-hand electrode of switch 3I9 is connected by wires 32| and 322 to terminal B of motor 3 0. By this arrangement, whenever the temperature of the water within tank 230 is above the setting of thermostat 3| 2 a short-circuit is completed between terminals R and B of motor 3I0,'which causes it to open valve |05 wide. The purpose of this arrangement is to avoid restricting the flow path for the circulating water whenever no heating is required for the water in tank 230. It should also be noted that the right-hand electrode of mercury switch 3|9 is connected by Wire 323 to the switch arm 43 of relay 31, while the in contact of this relay is connected by wire 324 to the wire 322. By this arrangement, when the relay 31 is energized for placing the system on the coolshort-circuited as follows: terminal R, Wire 320, right-hand electrodes of mercury switch 3I9, wire 323, switch arm 43, wire 324 and wire 322 to terminal B. This will cause the valve |05 to be opened wide whenever the system is operating on the cooling cycle. When the system is operating on the heating cycle and the thermostat 3I2 indcates that heating of the domestic water is desirable, the mercury switch 3I9 will be in the position shown and the switch arm 43 will engage its out contact. This will complete a circuit from terminal R of motor 3|0 to the slider 3 I 5 of thermostat 3| I as follows: terminal R, wire 320, right-hand electrodes of switch 3 I 9, wire 323, switch arm 43 and wire 325 to slider 3|5. The right-hand end of resistance 3I6 is connected to terminal W of motor 3|0 by wire 326 and the left-hand end of this resistance is connected to ermnal B by wire 321. Therefore, when the system operates on the heating cycle and heating of the domestic water is desirable, the thermostat 3| will be placed in control of the valve |05 for controlling this valve in a manner to maintain the desired temperature of the water leaving coil 2| of heat exchanger II. It will be notedthat a rheostat 328 is interposed in the circuit rto terminal W of motor 3|0 for thus preventing valve |05 from being completely closed under the control of thermostat 3| I. This will insure a continuous circulation of water through the system for thus maintaining the thermostat 3| I operative at all times and also insuring that the supply of heat to the coil |08 is never completely interrupted.

While I have shown the thermostat 3|2 for maintaining the valve |05 wide open whenever heat for domestic water is not required, it will also be understood that I contemplate substituting for this thermostat a pressure controller or in fact utilizing the pressure controller 242 in the control circuit of motor 3 I 0 in a manner to maintain the Valve wide open whenever heated water is not being supplied to the tank 230 The schematic diagram shown in Figure 3 illustrates the manner in which the pressure controller 242 may be utilized to control the circuit of the motor 3|0 to maintain the Valve |05 wide open whenever heated water is not being supplied tol the tank 230. Referring to this diagram it will be noted that the pressure controller 242 operates the mercury switch 330 in addition to the mercury switch 252 as shown in Figure 2, and that this switch 330 is substituted for the mercury switch 3I9 of Figure 2 which is operated by the thermostat 3I2. The temperature controller 3| I is connected to the motor 3 I 0 in the same manner as in Figure 2 and the mercury switch 252 in cornbination with the relay arm 42 functions in the same manner as in Figure 2. In Figure 3, however, the R terminal of the motor 3| 0 is now connected by means of the wire 332 to the common electrode of the mercury switch 330. The left hand electrode of the mercury switch is connected by wires 333, 322, and 33| to the B terminal of the motor 3 I 0 and the right hand electrode of the mercury switch 330 is connected to the relay arm 43 of the change-over relay 31 by means of the wire 334.

Thus, if the change-over relay 31 should be energized to place the system on the cooling cycle, the terminals R and B of the motor 3|0 may be short circuited by means of a circuit extending ing cycle, terminals R and B of motor 3|0 will be 75 from the R terminal of the motorv 3|0 through the wire 332, right hand electrode of mercury switch 330, wire 334, relay arm 43, wire 324, 322

and 33| back to the B terminal of the motor 3|0. This will cause the motor 3|0 to move the valve to wide open position. When the system is operating on the heating cycle and the pressure controller 242 indicates that heating of the domestic hot water is desirable, the mercury switch 330 will be in the position shown and the relay arm 43 will be in its out position because the change-over relay 31 will be deenergized at this time. This will complete a circuit from the R terminal of the motor 3 I0 through wire 332, to the common terminal of the mercury switch 330 and then through the right hand terminal of the mercury switch 330, through wires 333, 322, and 33| back to the B terminal of the motor 3|0. Therefore, at this time the valve |05 will also be opened wide. If the mercury switch 330 should be in its other controlling position indicating that heating of the domestic hot water is not necessary the R terminal of the motor 3|0 will be connected by means of the wire 332 to the common terminal of the mercury switch 330 and then through the right hand terminal thereof through wire 334 to the relay arm 43 which will be in its out position and thence through conductor 325 to the slider 3 5 of the temperature controller 3| Under these conditions, therefore, the position of the valve |05 will depend upon the temperature at the temperature controller 3| It will now be apparent that when the system operates on the heating cycle the pressure controller 242 is placed into control of the valve 24| and acts to open this valve whenever the supply of water within tank 230 requires replenishing.

Also it should be apparent that the valve |05 acts under the control of thermostat 3|| to maintain the temperature of the heated water at the desired value for domestic purposes and that this valve is caused to be Wide open whenever heated domestic Water is not required to be supplied to the tank 230. It will also be apparent that when the system is operating on the cooling cycle the valve 24| will remain closed and that the valve |05 will remain Wide open.

Operation With the parts in the positions shown, the outside temperature is at or above 90 F. as indicated by the slider |20 of the outdoor thermostat engaging the right-hand end of resistance |2|. This has caused the step controller motor ||3' to rotate shaft ||4 to its clockwise limit of rotation and this has caused closing of the mercury switches |24, |35 and |35. Due to closure of the mercury switches |24 and |35 the circulating pumps 8| and |00 are in operation. Also due to closure of the mercury switch |36 the changeover relay 31 is energized. Energization of this changeover relay, among other things, has caused positioning of the three-way refrigerant valves 1 and 8 in a manner to cause the heat exchanger to operate as an evaporator for cooling the Water and for causing the heat exchanger |4 to operate as a condenser. At this time the changeover relay 31 has placed the pressure controller 242 on tank 230 in control of the valve 238. Due to the pressure Within tank 230 being above the setting of controller 242, this controller has deenergized the relay device 245 for thus causing the valves 238 and 244 to be closed While the valves 89 and 92 are open. Therefore, at this time water is withdrawn from the well 85 by pump 8|, this water being passed through the coil 19 which acts as a precooler. The water leaving coil 19 then either flows through the reheater 81 or by-passes it, depending upon the temperature of the discharged air. If this temperature is above the setting of thermostat 91 the valve 96 will be open for thus permitting the reheater 81 to be by-passed, while if reheat is necessary the thermostat 91 will close Valve 95 for forcing the water through reheater 81. The water flows from this point through the pipe 88 and the open valve 89 to the coil 22 in heat exchanger |4 for thus condensing the liquid refrigerant within the refrigeration system. From this point the water passes through pipe 9| and the open valve 92 through pipe 93 to the sump 94 from which it may return to the well through the subterranean ditch 95 which causes this water to be cooled before returning to the well. At this time the heat exchanger is operating as an evaporator or water cooler and the pump |09 circulates water from this heat exchanger through storage tank |01a to the coil |08 in conditioning chamber 15 for thus causing the coil |08 to act as a cooling coil for cooling the air being supplied to the space. Due to the system now operating on the cooling cycle, the valve 05 at the discharge of pump |00 is caused to be opened Wide by the changeover relay 31.

With the system operating on the cooling cycle the changeover relay 31 places the space thermostat 200 in control of the step controller motor 45 which controls the compressor speed. With the parts in the position shown, the space temperature is at or above 80 F. as indicated by the slider |93l of thermostat 200 engaging the lefthand end of resistance 284. Also with the parts in the position shown, the temperature of the chilled cooling water is at 60 F. as indicated by the slider |15 of thermostat |62 engaging the right-hand end of, resistance |11. This has caused the slider |10 to engage the right-hand end of resistance |1| in spitev of the action of the potentiometer |8| which is actuated by the step controller ||0. Due to the limit controller |6| now exerting no limiting effect and due to the fact that slider 203 of thermostat 200 is engaging the left-hand end of resistance 204, the step controller motor |45 has positioned its shaft |46 for causing the compressor to operate at maximum speed. The space thermostat 200 will now control the compressor speed in a manner to decrease the compressor speed upon temperature fall and to increase the compressor speed upon temperature rise, thereby maintaining the space temperature within the range of the thermostat 200. However, the limit controller |6| will prevent the thermostat 200 from operating the compressor suflciently to reduce the cooling water temperature below a predetermined value, and this value is varied by the action of the potentiometer |8| in a manner to raise the limit controller control point upon rise in outside temperature and vice versa. This action of the limit controller |6| prevents the water temperature from being cooled further than necessary for maintaining the desired space temperature and thus avoids uneconomical operation of the system which might occur if the space thermostat alone controlled the compressor.

As water is Withdrawn from the tank 230 and the water level reaches the low limit value, the pressure controller 242 Will energize the relay device 245 which acts to open valve 238 under the control of thermostat 241 and to close valve 89 while opening valve 244 and maintaining the valve 92 open temporarily. This action in the manner previously described causes the well water to be by-passed around the coil 22 in heat exchanger I4 and also permits ushing out of this coil by city Water entering through pipe 231 and leaving the coil through the open valve 92. Then after a predetermined ushing period the relay device 245 closes valve 92 which causes the water passing from coil 22 to flow through pipe 234, check valve 235 and pipe 232 into the tank 230. When the water level within tank 230 is raised to the desired point the pressure controller 242 deenergizes the relay device 245, which causes closing of valves239 and 244 and opening of valves 89 and 92 for returning the system to normal operation.

As outside temperature falls, the slider |20 of thermostat ||I will begin moving to the left across resistance I2I, which will cause counterclockwise rotation of the shaft ||4 thus causing slider |82 of potentiometer IBI to shift upwardly along resistance |83, which has the effect of lowering the control point of the limit controller |6| to thus permit the chilled water temperature to be lowered correspondingly. This action is necessary in order to insure that the desired differential in temperature between the chilled water and outside air may be maintained for securing the necessary transfer of heat from the air to the cooling water. Due to falling of outside temperature, the cooling load upon the system willdecrease, which permits the space temperature to fall and in response to such falling space temperature the thermostat 200 will reduce the compressor speed to thus prevent overcooling of the space. When the outside temperature falls to 80 F. the cam ||6 of step controller IIO will cause tilting of mercury switch |35 to open position which will stop the pump |00. This will prevent further circulation of cold water between the heat exchanger |I and the coil |08. This stopping of the cooling water circulation will stop further supply of heat to the evaporator or water cooler II thus stopping the evaporation of liquid refrigerant within this device. Due to this action the compressor will eventually reduce the pressure within evaporator I and the suction side of the system as to cause the suction pressure controller |64 to operate for stopping the compressor. It will therefore be seen that when the outside temperature falls to 80 F. the circulating pump is stopped, which results in stopping of the compressor This is desirable as when the outside temperature is below 80 F. the cooling effect of the coil 19 will be sulcient for cooling the space suiciently, unless the outdoor air is nearly saturated.

When outside temperature falls to 70 F., the mercury switch |36 of step controller ||0 will be tripped for deenergizing the changeover relay 31. Deenergization of this relay will cause repositioning of the refrigerant valves 1 and 8 as well as the other refrigeration system valves for causing reversal in operation of the refrigeration system, thus causing the heat exchanger |I to operate as a condenser and to cause heat exchanger I4 to operate as an evaporator. The changeover relay will also place the compressor controlling step controller |44 under the control of the winter thermostat 20| which now acts to increase the compressor speed upon falling in space temperature and to decrease the compressor speed upon rise in space temperature in a manner to maintain the space temperature between '70 F. and 72 F. Deenergization of the changeover relay 31 will also act to place the pressure controller` 242 in control of the Water valve 24| and to place the valve |05 under the control of the thermostats 3| I and 3 I 2.

With the system in operation on the heating cycle, water is withdrawn from well by pump 8| and passed through the coil 19 in conditioning chamber 15. This coil now acts as a preheater for heating the cold incoming air with the relatively warm well water. Due to coil |08 acting as a heating coil, the discharge air thermostat 91 will be satised thus maintaining the Valve 96 open for permitting the water leaving coil 79 to by-pass the summer reheater 81. The water leaving the coil 19 will therefore flow through pipe 88, open valve 89 and pipe 90 into coil 2,2 of heat exchanger I4 which operates as an evaporator for absorbing heat from this water. This chilled water then iiows through pipe 9| and Valve 92 into the sump 94 from which it iiows back to the well 85 through subterranean ditch 95 which now acts to heat the water.

As mentioned above, the heat exchanger I I operates as a condenser during the heating cycle for thus supplying heated water to the coil |08. Due to the valve 24| now being under the control of the pressure controller 242, this valve will be opened whenever the water level in tank 230 falls to the low limit point. This will permit water to iiow from the supply pipe 236 through pipe 240 into coil 2| of heat exchanger I, passing through pipe |03, pump |00, valve |05, pipe |06, pipe 233 and pipe 232 into the tank 230. At this time the position of the valve |05 is controlled by the thermostat 3|| to throttle the flow of water in a manner to maintain the heated water temperature at the desired value. However, when the temperature of the Water within tank 230 is above the setting of thermostat 3I2 this valve will be maintained Wide open for thereby avoiding unnecessary restriction in water ow when heated domestic water is not required.

When the outside temperature is between 70 and 60 F. the cam I|5 of the step controller IIO will cause opening of switch |24 for placing the pump 8| out of operation. At this time very little or no heat will be required for heating the space and in fact the cold well water will be cooler than the air passing through the conditioner 15. It is thus desirable to stop iiow of well water through the coil 19 at such times for this would tend to cool the air passing to the space.

In most installations, the internal heat gain within the space will be suiicient to maintain the space temperature above the control point of the winter thermostat 20| until the outside temperature is well below 60 F., and consequently the compressor will not be placed into operation when the pump 8| is out of operation. Consequently, no provision is illustrated` for starting pump 8| when compressor I is placed into operation. For unusual applications of my invention in which the internal heat gain for the space is low, it may be desirable to provide for starting pump 8| when the compressor is started, in order to provide a source of heat for heat exchanger I4 which is then acting as an evaporator. This may readily be accomplished by a switch on step controller |44, which is connected in parallel with switch |24, or by a relay in parallel with switch |24 which is energized simultaneously with the compressor.

Due to the action of the storage tank |01a, heated water will be stored for heating the space when the system operates on the heating cycle, and cold water will be stored when the system I and ther 0,600, UUJ.

operates on the cooling cycle. Due to this storage effect, the necessary compressor capacity will be reduced. In the event that the stored medium is not satisfactory for either cooling or heating, the valve ID'Ic will be opened for permitting a portion of the medium to ow directly to heat exchanger |08, and this valve will remain open until the temperature of the medium leaving the tank is returned to a suitable value.

From the foregoing description it Will be seen that I have provided a reversible cycle refrigeration system for cooling a conditioned space in summer and for heating the space during the winter. It will also be seen that during both the heating cycle and the cooling cycle the system will automatically heat domestic hot Water. It will further be seen that my improved system utilizes a Well or other source of Water supply for absorbing heat removed from the space on the cooling cycle and for supplying heat tothe space on the heating cycle.

While throughout this description I have mentioned different values of temperature and pressures at which the various controls may operate, it Will be understood that these values are illustrative only and will vary for different installations and applications of my improved system. While I have shown and described a preferred form, it will be apparent that many modifications which are Within the scope of my invention will occur to those skilled in the art. I therefore desire to be limited only by the scope of the appended claims.

I claim as my invention:

1. In a system of the class described, in combination, a refrigeration system having an evaporator and a condenser, means for conditioning a space including a precooling device and a cooling device, means for passing a cooling medium through said precooling device and then in heat exchange relationship with said condenser, means for passing a heat exchange medium in heat exchange relationship with said evaporator and then through said cooling device, Y Lor varying the output of saidnrefrigeration syste.m inacgordance Witltlie`""ciling lo'ad'm vatie limi"`ii`iti"lWV sponsive to the temperuitm'tdf the heat exchange medium passing to said cooling device for additionally controlling said refrigeration system.

2. In a system of the class described, in combination, a refrigeration system having an evaporator and a condenser, means for conditioning a space including a cooling device connected to said evaporator for receiving cooling 'medium therefrom, means for varying the output of said refrigeration system in accordance with the cooling load, limit control means responsive to the temperature of the cooling medium passing to saidcooling device for controlling said refrigeration system, and outside temperature rea preheater or a precooler, and said second heat exchanger being arranged to operate leither as a heater or as a cooler, a refrigeration system including a first heat exchangeV device, a second heat exchange device, andf verswing oo nmtaioalmeans for selectively causinggiifatmwchange device to operate as an evaporator while said second heat exchange device operates as a condenser, or for causing said rst heat exchange device to operate as a condenser while said second heat exchange device operates as an evaporator, means for passing a heat exchange medium through said first heat exchanger and then into heat exchange relationship With said rst heat exchange device, means for placing said second heat exchanger and said second heat exchange device into heat exchange relationship, gamertag* stetige penitenciaria'. Said tank "bigjconnected/ tmthe i'tlets of b'dtfheat exchange devices, a source of mediumto be heated, and means for connecting said source to the first heat exchange device during the coolingseason, and to the second heat exchange device during the heating season.

4. In a system of the class described, first and second heat exchangers for either heating or cooling a space to be conditioned, said first heat exchanger being arranged to operate either as a preheater or a precooler, and said second heat exchanger being arranged to operate either as a heater or as a cooler, a refrigeration system including a rst heat exchange device, a second heat exchange device, and reversisraigg mawnswfllmslectiiielyacausing @..fliigadevic per. condenser, or 'iusing said irst heat exchange device to operate as a condenser while said second heat exchange device operates as an evaporator, means forpassing a heat exchange medium through said first heat exchanger and then into heat exchange relationship with said first heat exchange device, means for placing said second heat exchanger and said second heat exchange device into heat exchange relationship, a tank for storing heated medium, said tank being connected to the outlets of both heat exchange devices, a source of medium to be heated, means for connecting said source to the rst heat exchange device during the cooling season, and to the second heat exchange device during the heating season, and ther static valve means 45 for controlling the How heat exchange devices when each is acting as a ycondenser in a manner to maintain the temperature of the heated medium above a predetermned value. l

5. In a system of the class described, in combination, a refrigeration system for cooling a space to be conditioned, said refrigeration system including a condenser, a precooler for cooling said space, means for passing cooling medium through said precooler and then into heat exchange relationship with said condenser, a storage tank for domestic hot Water, a source of water to be heated, spdnsiyegtpwg demand fornijmhgtlwater in www 'nterrupt- (3Q ng e ffiv of cglgwm dium inv hea exchange relationship with said condenser and for passing said medium to be heated in heat exchange relationship with said condenser.

6. In a System of the class described, in conibination, a refrigeration system for conditioning a space, said refrigeration system including a condenser, a tank for storing a heated medium, means for passing medium to be heated in heat exchange relationship with Said condenser for coo-ling said condenser and heating said medium, means for passing the heated medium to said tank, flow control means for controlling the now of said medium, a1 1 cll- M in egaifisnresponsive to the temperature of the stlgrpidmeatingemedium and to the temperature of the'heated medium iiowing Nun-"M to said tank for controlling said flow control means.

'7. In a system of the class described, in combination, a refrigeration system for cooling a space to be conditioned, said refrigeration system including a condenser, means for passing cooling medium through said condenser for cooling said condenser, a tank for storing heated medium, a source of medium to be heated, means actuated upon devrnandnion--heated medium to l0 interrupt the flw of cooling medium in heat exchange relationship with said condenser, and to pass medium from said source in heat exchange relationship with said condenser, valve means for permitting a flushing action by said f--'medium aMathers.geeaseasailsiaeser! Valve.

" means to be operated after a predeternnr'iedflish ing period to cause said heated medium to flow to said tank.

8. In a system of the class described, in combination, a refrigeration system for conditioning a space, said refrigeration system including a condenser, a tank for storing a heated liquid, said tank being closed at its upper part for trapping a gas above the liquid therein, means for passing said liquid in heat exchange relationship with said condenser and into said tank, flow control means for controlling the flow of said liquid in heat exchange relationship with said condenser, mgans responsive to the temperature and means responsiveito the liquid levelwinmsaid tank for controlling said forcing means.

9. In a combined heating and cooling system, in combination, heat exchange means for either heating or cooling air in a space, a reversi-ble refrigeration system for selectively supplying hot or cold heat exchange medium to said heat exchange means, a storage tank for the heat exchange medium interposed between said heat exchange means and said refrigeration system, a

by-pass around said storage tank, a valve in said by-pass, and meagskrespo ture of the medium in sai said valve.

10. An apparatus for supplying water for both the tempera- QYII.. Controlling heat exchange and domestic use, said apparatus 5 comprising a heat exchanger, a line for supplying water thereto, a modulating valve in said line, thermostatic means for automatically controlling said modulating valve in accordance with the demands made upon said heat exchanger to vary the rate of flow of water therethrough from the supply line, a line from the outlet of said heat exchanger connecting with a domestic water supply system, and valved means operated in response to pressure in the apparatus to relieve the apparatus of water flowing through the heat exchanger in excess of domestic requirements while maintaining in said domestic system a supply of water under adequate pressure,

the last mentioned means being connected to the second mentioned line at a point between said heat exchanger and said domestic water supply system.

l1. In a system of the class described, in combination, a refrigeration system for conditioning a space, said refrigeration system including a condenser, a tank for storing a heated medium, means for passing medium to be heated in heat exchange relationship with said Condenser for cooling said condenser and heating said medium,

means responsive to a demand for heated medium in said tank for causing a flow of said heated medium to said tank, ow control means for controlling the ow of said medium in heat exchange relationship with said condenser, and means responsive to the temperature of the heated medium for controlling said flow control means in a .manner to restrict the flow upon 4fall in temperature to thereby maintain the temperature of the heated medium at a predetermined value, said demand responsive means operating when the demand for heated medium in. said tank is satisfied to prevent the further delivery of heated medium to said tank and also to maintain said flow control means in maximum flow condition irrespective of said temperature responsive means. f

12. In an air conditioning system for a space, first and second heat exchangers, means forcibly circulating a medium through said iirst exchanger, said medium having a substantially constant temperature slightly lower than the desired temperature of said space whereby said rst heat exchanger acts as a precooler in summer and a preheater in winter, means forcibly circulating a medium through said second heat exchanger, means for heating said last named medium for winter operation, refrigeration means for cooling said last named medium for summer operation, and means responsive to outside `temperature for rendering said heating or cooling means effective depending upon whether said temperature is below or above a predetermined intermediate value, said outside temperature responsive means including means for stopping circulation of said medium through said second heat exchanger when said outside temperature is within a range between said intermediate value and a higher value during which said precooler is sufcient to maintain the temperature in said space at a desired value.

13. In an air conditioning system for a space,

n rst and second heat exchangers, means forcibly circulating a medium through said first exchanger, said medium having a substantially constant temperature slightly lower than the desired temperature of said space whereby said first heat exchanger acts as a precooler in summer and a preheater in winter, means forcibly circulating a medium through said second heat exchanger, means for heating said last named medium for winter operation, refrigeration means for cooling said last named medium for summer operation, and means responsive to outside temperature for rendering said heating or cooling means effective depending upon whether said temperature is below or above a predetermined intermediate value, said outside temperature responsive means including means for stopping circulation of said medium through said second heat exchanger when said outside temperature is within a range between said intermediate value and a higher value during which said precooler is sucient to maintain the temperature in said space at a desired value, said outside temperature responsive means also including means for stopping the circulation of medium through said rst heat exchanger when said outside temperature is between said intermediate value and a predetermined lower value at which time no artificial heating is required to maintain the desired temperature within said space.

ROBERT B. P. CRAWFORD. 

